Oxygen　evolution　reaction　(OER)　plays　a　critical　role　in　energy　conversion　technologies.　Significant　progress　has　been　made　in　alkaline　conditions.　In　contrast,　it　remains　a　challenge　to　develop　stable　OER　electrocatalysts　in　acidic　conditions.　Herein,　a　new　strategy　is　reported　to　stabilize　single　atoms　integrated　into　cobalt　oxide　spinel　structure　with　interstitial　carbon　(Ru0.27Co2.73O4),　where　the　optimized　Ru0.27Co2.73O4　exhibits　a　low　overpotential　of　265,　326,　and　367　mV　to　reach　a　current　density　of　10,　50,　and　100　mA　cm2,　respectively.　More　importantly,　Ru0.27Co2.73O4　has　long-term　stability　of　up　to　100　h,　representing　one　of　the　most　stable　OER　electrocatalysts.　X-ray　adsorption　spectroscopy　(XAS)　characterization　and　density　functional　theory　(DFT)　calculations　jointly　demonstrate　that　the　significant　catalytic　performance　of　Ru0.27Co2.73O4　is　due　to　the　synergistic　effect　between　the　Ru　and　Co　sites　and　the　bridging　O　ligands,　as　well　as　the　significant　reduction　of　the　OER　energy　barrier.　This　work　provides　a　new　perspective　for　designing　and　constructing　efficient　non-noble　metal-based　electrocatalysts　for　water　splitting.　The　mechanism　behind　the　synergistic　effect　of　hybridization　between　noble　metal　and　non-noble　metal　oxide　supports　is　not　yet　clear.　Here　them　first　demonstrated　that　the　introduction　of　interstitial　C　can　effectively　enhance　the　stability　and　activity　of　Co3O4　by　controlling　the　evaporation　and　combustion　of　C　in　air.　The　Ru0.27Co2.73O4　electrocatalyst　shows　extremely　high　mass　activity　and　significantly　improve　the　corrosion　resistance　of　acidic　oxygen　evolution　reaction.image